One basic element in the control of human movement is the ability to correctly adjust the magnitude and temporality of muscle contractions to meet the requisites of precision-demanding motor tasks. Tracking experiments have been advocated as an ideal protocol for quantitating such skillful performance. See K. Cross, Role of Practice in Perceptual-Motor Learning, 46 Am. J. Phy. Med. 487-510 (1967); E. Poulton, Tracking Skill and Manual Control, New York, Academic Press, Inc. (1974); R. Jones & I. Donaldson, Measurement of Integrated Sensory-Motor Function Following Brain Damage By a Computerized Preview Tracking Task, 3 Int. Rehab. Med. 71-83 (1981); A. Potvin & W. Tourtellotte, Quantitive Examination of Neurological Functions, Vols. 1-2, Boca Raton, FL, CRC Press, Inc. (1985).
Tracking is the effort to accurately pursue some desired target by careful adjustment of the intensity and timing of muscle contractions, and is guided by the surveillance of one or more sensory cues. The desired target may be a certain force level, joint angle, eye position or the precise placement of an object in space. Common examples of tracking in daily living include: accurately reaching for an object, visually following a moving object, steering a vehicle, and handwriting. All of these activities involve a closed-loop negative feedback mechanism of control whereby ongoing integration between a faithful sensory system and a responsive motor system is used to minimize the undershoot or overshoot error about the desired target.
Measurement of tracking performance as an indicator of motor control has been documented as early as 1922. See W. Koerth, A Pursuit Apparatus: Eye-Hand Coordination, 31 Psychological Monographs 288-92 (1922). A particular surge of interest in this topic occurred during and immediately after World War II with a focus on gunnery skills. See C. Kelley, The Measurement of Tracking Proficiency, 11 Human Factors 43-64 (1969). Psychologists and educators have utilized tracking tests as a method of elucidating some of the intricacies of motor-control learning. See R. Eason & C. White, Relationship Between Muscular Tension and Performance During Rotary Pursuit, 10 Percept. Mot. Skills 199-210 (1969); C. Frith, Learning Rhythmic Hand Movements, 25 Q. J. Exp. Psych. 253-59 (1973); M. Abrams & J. Grice, Effects of Practice and Positional Variables in Acquisition of Complex Psychomotor Skill, 43 Percept. Mot. Skills 203-11 (1976); S. Hogan, H. Wilkerson & C. Noble, Pursuit Tracking Skill as a Joint Function of Work and Rest Variables, 50 Percept. Mot. Skills 683-97 (1980). Medical science has employed tracking experimentation as a means of documenting motor control in individuals with such neuromuscular conditions as Parkinson's disease, see K. Flowers, Visual "Closed-Loop" and "Open-Loop" Characteristics of Voluntary Movement in Patients with Parkinsonism and Intention Tremor, 99 Brain 269-310 (1976); K. Flowers, Some Frequency Response Characteristics of Parkinsonism on Pursuit Tracking, 101 Brain 19-34 (1978), cerebella ataxia, see H. Beppu, M. Suda & R. Tanaka, Slow Visuomotor Tracking in Normal Man and in Patients with Cerebellar Ataxis, 39 Advances in Neurology 889-95 (1983); H. Beppu, M. Suda & R. Tanaka, Analysis of Cerebellar Motor Disorders of Visually Guided Elbow Tracking Movement, 107 Brain 787-809 (1984), multiple sclerosis, see W. Henderson, W. Tourtelloute & A. Potvin, Training Examiners to Administer A Quantitative Neurological Examination for a Multicenter Clinical Trial, 56 Arch. Phys. Med. Rehabil. 289-95 (1975); A. Potvin & W. Tourtellotte, The Neurological Examination: Advancements in its Quantification, 56 Arch. Phys. Med. Rehabil. 425-37 (1975), and head trauma, see R. Jones & I. Donaldson, Measurement of Integrated Sensory-Motor Function Following Brain Damage By a Computerized Preview Tracking Task, 3 Int. Rehab. Med. 71-83 (1981); L. DeSouza, R. Hewer, P. Lynn, S. Miller & G. Reed, Assessment of Recovery of Arm Control in Hemiplegic Stroke Patients: Comparison of Arm Function Tests and Pursuit Tracking in Relation to Clinical Recovery 2 Int. Rehab. Med. 10-16 (1980).
These contributions to the concern of motor control in humans are commendable; however, the fruits of these valuable efforts have not been fully exploited in rehabilitation. Heretofore procedures of measuring motor control have included such tests as reaction time, movement time, reciprocal tapping, and peg transfer. See L. Carlton, Movement Control Characteristics of Aiming Responses, 23 Ergonomics 1019-32 (1980); R. Schmidt, Motor Control and Learning, Champaign, Human Kinetics Pub. (1982). While each of these tools does yield information about certain ingredients of motor control, they do not provide the desired objective quantitation of an individual's ability to actuate the precise level and punctuality of muscular activity required by a specific motor task.
There still exists a critical need to quantify the efficacy of various therapeutic procedures purported to improve motor function in disabled individuals. Documentation related to muscular strength certainly abounds in the literature. And although the capacity to exert strong muscular forces is advantageous to an individual, the great preponderance of activities of daily living require, not so much strong efforts, but rather well-controlled efforts typically within the individual's existing force range.
Tracking experiments provide a rigorous and objective method with which to obtain such documentation of motor control. This invention describes a method and instrumentation for quantitating functional motor performance using pursuit tracking scores and determining the sensitivity of this method in detecting improved performance in normal individuals resulting from limited practice at a series of paced tracking tasks.